Currently, there are many kinds of computer mouse available on the market, which are the most popular human-machine interface used by computers as cursor-control device. Most of computer mice are only operable on a planar surface, such as a desk-top, and are generally to be an optical mouse. There are two most common types of optical mice available nowadays, which are LED optical mouse and laser mouse with respect to the different means of detection. A typical LED optical mouse has a small, red light-emitting diode (LED) that bounces light off that surface with sufficient roughness onto a complimentary metal-oxide semiconductor (CMOS) sensor. The CMOS sensor sends each image to a digital signal processor (DSP) for analysis, that the DSP is able to detect patterns of shadows generated by the roughness of the surface in the images and see how those patterns have moved since the previous image. Based on the change in patterns over a sequence of images, the DSP determines how far the mouse has moved and sends the corresponding coordinates to the computer. However, if the working surface of the LED optical mouse is a smooth surface made of marble, tile, or metal, etc., such mouse might not be able to operate without a hitch. A laser mouse is an advanced optical mouse, which is capable of emitting a coherent light so as to detect more surface pattern variation than the standard LED based optical mice. Nevertheless, such laser mice are not able to operate fluently while working on a transparent surface made of glass, acrylic, and so on.
With respect to the shortcomings of optical mice, inertial cursor-control devices, such as the inertial mouse disclosed in T.W. Pat No. 526975, are gradually becoming popular on the market. The inertial mouse is more versatile than conventional optical mouse since it can be adapted to operate fluently;on all most any type of surface. However, when operating an inertial cursor-control device on a planar surface, the operation of the inertial cursor-control device is usually limited by the size of the surface. That is, when the operating of an inertial cursor-control device brings it to the position near the edge of its operating surface, it is often required to pick up the inertial cursor-control device and put it back to the center of the surface. During the pick-up and put-back period, the inertial sensor of the inertial cursor-control device, such as an accelerometer, is still operative for, detecting the status of the inertial cursor-control device and is subject to the influence of gravity, such that the inertial sensor will pick up unwanted signals and cause the cursor controlled thereby to move disorderly and unexpectedly on the display.
Therefore, what is needed and would be useful is a status sensing mechanism, arranged in a inertial cursor-control device, capable of detecting and determining the operation of the inertial cursor-control device.